The Mechanical Performance of Traditional Adobe Masonry Components: An Experimental-Analytical Characterization of Soil Bricks and Mud Mortar

Abstract

Adobe is an ancient building technology made of sun dried bricks joined together by mud mortar. This paper deals with the physical and mechanical characterization of three different typologies of adobe bricks and one typology of mud mortar produced in Europe. They differed in terms of internal soil element proportions and amount of organic content. Physical tests consisted of granulometry, moisture content and density tests. The mechanical characterization consisted of uniaxial compressive tests and three point bending tests. Tests were performed according to modern material standards. The main mechanical properties both in tension and compression were determined at different curing conditions. The outcome provided in this study offers a general overview on the assessment of the mechanical performance of adobe in relation to the properties and interactions of its soil constituents. In fact, the comparison between components with the same soil mineralogical family and production process made it possible to assess both at a qualitative and quantitative level the effect of the physical properties of the mixture (such as fiber and clay percentages or moisture content) on the mechanical parameters of the resulting bricks and mortar. This paper proposes new predictive formulations of the most relevant material parameters in strength and deformation, such as compressive strength, deformation at peak stress and ultimate displacement for both adobe bricks and mortar. They quantify the influence that water content, clay percentage and fiber reinforcement produce on the mechanical performance of the tested adobe components. This was made possible by means of multivariate statistical analyses on the mechanical parameters derived from all the tested samples.

Development of a dataset on the in-plane experimental response of URM piers with bricks and blocks

“…This situation occurs because this building technology was progressively abandoned starting from industrial revolutions in favour of modern materials introduced in the construction market [25]. Nevertheless, in recent times Adobe has gained scientific interest, as a result of a specific socio-economic conjuncture [26]. Earthen buildings, which provide shelter to more than one third of the world population constituting 10% of the built heritage [27], are spread in areas of the world prone to natural hazards or involved into military operation, with the related treats for human beings and their property.…”

Dynamic characterization of adobe in compression: the effect of fibre fraction in soil matrix

“…2 of lower strength values associated to bricks mixed with fibers in statics. This is actually a common trend in literature and only in rare cases inclusion of fibers determine higher mechanical performance in adobe [4]. This can be explained assuming that fibers constitute weak interfaces of the meso-structure and their inclusions in soil mixtures potentially determine extensive areas of de-adherence between the adopted soil matrix and natural organic materials, which enhance porosity in the mixture and exasperates the material heterogeneity [24].…”

“…Overestimation is even enhanced if the values of the reference parameters in eq.1 (f b and˙ s ) are adapted to the tests performed on Adobe. This is shown in the second plot of Figure 5, where the f b of the CEB is equal to 1.35 MPa, taken as the average of the compressive strength of 110 static tests collected from literature for traditional adobe in [4]. Little literature is concerned with the study and evaluation of the dynamic increase factors for steel fiber reinforced concretes [16,17].…”

“…As a result, SFRC is effective on resisting high loading rate impacts with lower penetration depth or residual velocity values in case of ballistic conflicts [3]. Actually, mixing matrices with fibers is not a new practice but starts with the use of adobe in the history of construction materials, a masonry of raw earthen bricks and mud mortar [4]. Raw mixtures of soil have been mixed using randomly distributed fibers locally available in the field since ancient Egypt and earlier [5].…”

“…Raw mixtures of soil have been mixed using randomly distributed fibers locally available in the field since ancient Egypt and earlier [5]. However, the reason for this inclusion in Adobe is mainly due to the need of preserving structural integrity and to prevent initial damage during shrinkage inherent air drying processes under sun of cast mixtures [4]. Instead, the effects of such inclusion on the mechanical performance of soil mixtures have been scarcely addressed in literature.…”